1. Field of the Invention
This invention relates to transfer of fluid to achieve shock absorption in footwear, and in particular, relates to fluid transfer for shock absorption and ankle support adjustable to compensate for differences in shoe size or body-weight of a user.
2. Background of the Prior Art
The basic concept of shock absorption in shoes with transfer of fluid between the heel to the ball portion of a user's foot has been known as illustrated in previously issued U.S. Patents. For example, U.S. Pat. No. 4,312,140 by Reber discloses a device to facilitate pedestrians comprising a heel cavity that is connected via a feedback tube to a cavity located in the front part of the sole of a shoe. The '140 patent teaches that when the heel impacts the ground the compression results in a closing of the feedback tube which is connected to a first reservoir which includes a first one-way valve thus causing a decrease in the inner volume. As a result of this decrease of volume, pressure inside the first reservoir increases. The specification explains that when this pressure reaches a certain value, the first one-way valve opens, so that the pressurized fluid under pressure can now flow through the tube and be stored, while a second controlled one-way valve remains closed. Intensity of reaction of the device may be adapted to the body-weight of the person wearing the shoes. During what is described as a second phase, the rear and front parts of the bottom part of the shoe are both simultaneously touching the ground. In this second phase, the device remains in the state reached at the end of the first phase, which means that a certain quantity of fluid under pressure is stored in intermediate storage means.
Another example of footwear having improved shock absorption is illustrated in U.S. Pat. No. 4,446,634 by Johnson et al. The '634 patent discloses a shoe containing fluid in both a shock absorption bladder in a heel portion and ball portion of the shoe. When walking and in most running, when the heel strikes the ground or support surface, the force in the heel portion will force fluid to flow in only one direction through a regulating valve. As the weight of the user is transferred from the heel portion to the ball portion of the foot, fluid is forced from the ball bladder through another regulating valve. Fluid can flow from the ball bladder to the heel bladder and vice versa, only in one direction, because of the orientation of check valves. This permits fluid to flow from bladder to bladder and prohibits fluid flowing in the opposite direction. The rate at which fluid flows from the heel bladder to the ball bladder and vice versa, can be adjusted by the operation of regulating valves.
U.S. Pat. No. 5,375,346 by Cole et al. discloses a shoe construction having heel and metatarsal bulges molded in the outer sole to define fluid-containing cavities. The bulges engage the ground as the wearer of the shoe is standing. The air in the cavities provides a cushioning effect. In walking and running, the heel bulge first comes in contact with the ground causing air in the cavity to be compressed and forced through a first passageway into the metatarsal cavity. As the heel portion lifts off the ground and the metatarsal bulge contacts the ground, the air in the metatarsal cavity is forced through a second passageway back into the heel cavity to give a lifting effect. Thus, in walking and running, the air alternates back and forth between the cavities.
The foregoing references are not exhaustive but illustrative of the state of the art and suggest that transfer of fluid can be employed to achieve shock absorption in footwear. The prior art however has not recognized or provided a solution to successfully apply the principle of fluid transfer for ankle support in shoes generally and particularly in running shoes. In addition, prior art fluid transfer devices are constructed based upon predetermined conditions applicable regardless of variations in shoe size or weight of the user.
What is needed is shock absorption footwear to facilitate metered fluid transfer throughout the foot and ankle, thus providing support for a user. It is also desirable to design a method and apparatus for pre-determining the compression pressure level to accomplish fluid transfer based upon the weight or shoe size of a person wearing the shoe.
The foregoing prior art references nowhere teach use of a combination of features in shoe structure that will provide the advantages of cushioning and shock absorption in separate regions of the foot in addition to providing support for the shoe wearer. Additionally, the prior art does not provide shoe structure capable of a quick and simple technique to vary and adjust the pressure within a fluid cavity corresponding to the weight or shoe size of the wearer.
The advantages of the present invention include the use of a forward and a rear tube cavity that extend around the perimeter of the shoe. The forward tube extends from approximate the in-step or arch region to the toe of a user and intersects with a plurality of transversely extending metatarsal inlets or projections. The forward tube is linked to the rear tube through pressure sensitive check valves. The rear tube extends around the shoe perimeter from approximate the in-step to the heel of a user, intersecting with a plurality of transversely extending arch inlets and a plurality of upwardly extending projections that surround and support the ankle of a user. The internal pressure within the forward and rear tubes is pre-determined based upon the weight or shoe size of the person wearing the shoe.
Other advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.